Mn-Doped SnO2 thin films were grown on sapphire (012) substrates by pulsed laser deposition. The influence of substrate temperature on the film properties was investigated. X-ray diffraction patterns show that the thin films grown at lower substrate temperatures were amorphous, while those grown at higher temperatures had only a single (101) orientation. Atomic force microscopy results indicate that the films grown at low temperature were extremely flat and they became rougher as substrate temperature (Ts) increased. Optical transmission spectra reveal that the absorption edge shifts
towards the blue side and becomes steeper at increasing Ts. High-resolution transmission electron microscopy analysis clearly indicates that the samples have a well-arranged tetragonal structure without any detectable secondary phase. Inhomogeneous incorporation of Mn atoms into the SnO2 lattice was also observed.